AEG Tappet Plate Timing: Check the Complete Cycle

Tappet plate timing is the relationship between the sector-gear tappet pin, tappet plate, nozzle and the rest of the gearbox cycle. A feeding symptom does not identify one failed part by itself. Check movement, release and return as a sequence before changing components.

Follow the movement

During a manual cycle, the tappet pin contacts the tappet plate and moves it rearward. The nozzle follows. When the pin releases the plate, the spring returns the plate and nozzle forward. Observe when each stage starts and whether the parts move freely.

Check the surrounding parts

• Inspect the tappet contact surface and spring.
• Verify the nozzle’s required listed length and matching profile.
• Check sector-gear clearance and piston engagement.
• Look for rubbing against the gearbox shell or hop assembly.

Do not confuse timing with stroke

A delayer chip can change contact duration, while sector geometry and tappet components affect other parts of the cycle. Changing one item does not prove that nozzle travel or feeding has been corrected. Use a manual cycle first, then short controlled tests.

For the design-specific role of the pin, read what the tappet plate pin position changes.